Here's one I read as a teenager... I'm guessing it's in the Young Adult genre, probably SF?
Set in a future earth, characters in the books are assigned different jobs after high school. The protagonist gets a job which she? (I think?) thought would be disappointing. What ends up happening is that this character ends up working with a group of maybe a dozen others exploring virtual worlds. They are hooked into a variety of equipment and have to face different challenges in the virtual worlds. They may live in the virtual world for a long time, days perhaps? However, when someone makes a (fatal) mistake, they all wake up. Some examples of such mistakes are eating poisonous berries (they saw birds eating them, so should be alright, right?), falling off a cliff, etc.
In the end they find out that they were part of a secret training project to colonize a distant planet. There were many such groups involved in training and they are all blasted off to a new planet, which has similar environments to their training worlds, but is significantly harsher. The various groups must learn to survive and cooperate with one another. I seem to remember some fighting, eventual peace and propagation of the human race through children.
I'd like to read this again now that I'm an adult and see if it was as good as I remember. Any ideas?